Primaquine  is indicated for the radical cure (prevention of relapse) of vivax malaria. 

Malaria

In a region where vivax malaria is endemic, primaquine phosphate is only advised for the radical cure of vivax malaria, the prevention of relapse in vivax malaria, or following the discontinuation of chloroquine phosphate suppressive therapy.
Primaquine phosphate, at a dose of 1 tablet (equal to 15 mg base) daily for 14 days, should be given concurrently to remove exoerythrocytic parasites.

• Gastrointestinal: nausea, vomiting, epigastric distress, and abdominal cramps. 
• Hematologic: leukopenia, hemolytic anemia in glucose-6-phosphate dehydrogenase (G-6-PD) deficient individuals, and methemoglobinemia in nicotinamide adenine dinucleotide (NADH) methemoglobin reductase deficient individuals. 

Nausea

Abdominal Pain

Leukopenia

• Because excessive dosages of primaquine have been linked to anemia, methemoglobinemia, and leukopenia, the adult dose of 1 tablet (= 15 mg base) daily for fourteen days should not be exceeded. During treatment, routine blood exams (especially blood cell counts and hemoglobin levels) are also recommended.
• If primaquine phosphate is prescribed for
  1. an individual who has previously shown an idiosyncrasy to the drug (as manifested by hemolytic anemia, methemoglobinemia, or leukopenia),
  2. an individual with a family or personal history of favism, or
  3. an individual with erythrocytic glucose-6-phosphate dehydrogenase (G-6-PD) deficiency or nicotinamide adenine dinucleotide (NADH) methemoglobin reductase deficiency, the person's tolerance should be regularly monitored. If there is a significant darkening of the urine or a quick drop in hemoglobin concentration or leukocyte count, the medicine should be stopped promptly.
• If you notice signs of hemolytic anemia, stop taking Primaquine phosphate right away (darkening of the urine, marked fall of hemoglobin or erythrocytic count).